Process for the production of aluminum castings and molds for use therein



3-; ep'atntea Aug. 1

UNITED STATES PATENT OFFICE.

EUGEN STRASSEB, OF BORSOHACH, SWITZERLAND, ASSIGNOB TO MAX DIETIKEB, OI ZURICH, SWITZERLAND.

PROCESS FOR THE PRODUCTION OF ALUMINUM OASTINGS AND HOLDS FOR USE TEEREIN.

No Drawing. Application filed December 7,

This invention relates to the production of aluminum castings, which term includes cast-' ings of aluminum alloys, for example aluminum-zinc castings, and to molds for use 5 therein.

The object of the invention is to enable chilled aluminum castings to be produced having high grade mechanical and physical properties.

According to the invention the mold in which the aluminum casting is to be effected is made of a mixture of molding sand and metal or metallic or metalliferous compounds, in a divided form for instance in a granular, pul- 1 verulent or powdered form.

The mixture is preferably effected while the sand is in a loose state and so that the metal, or metallic, or metalliferous material is uniformly distributed throughout the sand. 29 When an aluminum casting is made in a mold of this nature the resulting casting has high grade mechanical and physical properties. Particularly good results are obtained with alloys of aluminum and zinc. or zinc and other and more difliculty fusible metals. 4

When an aluminum zinc alloy such, for example, as the so-called German allo} is used as the metal to'be cast a most surprising result is obtained. This alloy. which contains 10% of zinc. 2% of copper and 88% of aluminum. and hitherto having comparatively low grade qualities, shows a marked improvement, its properties considerably surpassing for instance those of pure aluminum, that is cast- 35 ings of this hitherto low grade alloy can be produced exhibiting mechanical properties which are far above those of all aluminum alloys hitherto reaardedas his h grade. The product of the process according to the invention is principally intended to rank as a specificallv lighter substitute for cast iron, particularly grey cast iron and is. distinguished mainlv bv its high resistance to fracture. its limit of elasticitv, Brincll hardness and the ease with which it can be worked with cutting tools like a good brass.

Fnrth r' vnnta ee 'm 1w obtained are the 1925, Serial No. 73,866, and in Germany December 13, 198.

ease with which the mold can be produced and m the uniform composition'throughout the whole of the mold which is necessary for the 60 final product.

The better result may depend inter alia on the better permeability of the mold and the possibility thus afforded of the mold taking up and carrying off more moisture, both dur- 65 mg and after the casting operation, but particularly that a more uniform cooling action is obtained.

The best results as regards mechanical properties become manifest after a period of 60 about fourteen days, after casting.

Examples of ores or metalliferous materials which give good results are chalcocite (copper glance) Cu S, or chalcopyrites (copper pyrites) CuFeS,.

These materials are roasted, and in the roasting process. crumble to a fine powder which is highly suitable for the purpose.

Copper powder or filings may also be used effectively.

The proportions of molding sand and additive employed to form the molding mixture vary according to the nature of the casting to be produced, for example in the production of castings having a thickness of wall of say 10 5 to millimetres, a mixture composed of 75% molding sand and additive will be found satisfactory. whereas for castings having a thickness of wall of 15 to millimetres, a molding mixture composed of molding so sand and 50% additive is more suitable, while for castings having a thickness of wall of 30 to 45 millimetres the molding mixture may be composed of 25% molding sand and 75% additive. I

It is unnecessary to subject material ob-- tained by the present process to hot or cold treatment for ageing purposes, as is necessary in the case of duralumin for example, and

it is found that the damper the molding com- 90 position the greater is the ageing efi'ect. The addition of zinc to the metal to be cast should not exceed18%.

1. A process for the production of chilled state, substantially as and for the purpose 10 aluminum castings which consists in casting hereinbefore set forth. the molten aluminous material in a mold com- 3. A mold, for use in the casting of alumiposed of a mixture of molding sand and num castings, composed of molding sand and 5 roasted copperore in a, finely divided state, finely divided chalcocite, substantially as and for the purpose hereinbefore set forth. for the purpose hereinbefore set forth.

2. A mold, for use in the casting of alumi- In testimony whereof I a'ifix my signature. num castings, composed of a mixture of molding sand and copper ore in a finely divided EUGEN STRASSER. 

